Hypersialylation in tumor cells is a potent mechanism of tumor immune evasion, pushing cancer progression by suppressing both innate and adaptive antitumor immunity. Shanghai Henlius Biotech Inc. has developed an engineered human sialidase enzyme fused to an anti-B7-H3 nanobody, named E-688 or HLX-316, that improves tumor desialylation, durability and efficacy both in vitro and in vivo, while maintaining a safe profile.